This letter proposes a statistical cooperative scheme for transmit antenna subset selection in multiple-input multiple-output (MIMO) multicell systems. The proposed scheme is practical in that it only utilizes the statistical information for the adjacent links. However, it provides almost 90 percent of the average mutual information of the full cooperative scheme which requires a large amount of t...
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In this paper, we study the temporal behavior of narrowband fixed outdoor wireless channels by modeling the impact of scatterers' mobility on the second order statistics of such channels. We show that the Nakagami-m, gamma, Weibull and lognormal probability density functions (PDFs) can adequately approximate the scatterers' mobility at outdoor environments by comparing the theoretically derived au...
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In this letter, we propose two full-rate space-time-frequency trellis code (STFTC) designs for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The first proposal based on rotating constellation is called extended super-orthogonal STFTC (Ex-SOSTFTC). The second proposal, called Quasi-Orthogonal STFTCs (QOSTFTCs), combines set partitioning and the str...
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In this paper, we design a multiuser two-way relay system using space division multiple access (SDMA) communications and devise an optimal scheduling method that maximizes the sum rate while ensuring fairness among users. To reduce the computational load at the relays, we propose rate- and angle-based suboptimal scheduling methods. The numerical results illustrate tradeoff between complexity and t...
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Two kinds of iterative sphere detectors based on modifications of the Schnorr-Euchner enumeration are presented. The first is capable of finding "good" candidate lattice points relatively soon. Its complexity and performance are controlled by an adaptive radius backlash update strategy. The second systematically searches for the most contributive term in each of the two log-sum-exponents. Both kin...
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We consider a half-duplex mesh network wherein a single source communicates to a destination with the help of N potential decode-and-forward relays. We develop the optimal selection of a relaying subset and allocation of transmission time. This resource allocation is found by maximizing over the rates achievable for each possible subset of active relays; in turn, the optimal time allocation for ea...
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Many sensor network applications require the tracking and the surveillance of target objects. However, in current research, many studies have assumed that a target object can be sufficiently monitored by a single sensor. This assumption is invalid in some situations, especially, when the target object is so large that a single sensor can only monitor a certain portion of it. In this case, several ...
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This paper presents a MAP estimation method allowing the robust decoding of compressed video streams by exploiting the bitstream structure i.e., information about the source, related to variable-length codes and source characteristics) together with the knowledge of the MAC layer CRC (here considered as additional redundancy on the MAC packet). This method is implemented via a sequential decoding ...
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We present a mathematical model for communication subject to both network interference and noise. We introduce a framework where the interferers are scattered according to a spatial Poisson process, and are operating asynchronously in a wireless environment subject to path loss, shadowing, and multipath fading. We consider both cases of slow and fast-varying interferer positions. The paper is comp...
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In Part I of this paper, we presented a mathematical model for communication subject to both network interference and noise, where the interferers are scattered according to a spatial Poisson process, and are operating asynchronously in a wireless environment subject to path loss, shadowing, and multipath fading. We determined the distribution of the aggregate interference and the error performanc...
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To achieve a long run-time for battery-operated portable electronic devices that incorporate wireless transceivers, efficient power management of the radio is a critical requirement. The power management function of IEEE 802.11 wireless local area networks (WLANs) allows stations (STAs) to operate in the doze mode so that their power consumption is significantly reduced. Hence, efficient algorithm...
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In this paper, we study the minimum-latency broadcast scheduling problem in the probabilistic model. We establish an explicit relationship between the tolerated transmission-failure probability and the latency of the corresponding broadcast schedule. Such a tolerated transmission-failure probability is calculated in the strict sense that the failure to receive the message at any single node will l...
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Power management and energy-aware communications systems have become increasingly important in mobile computing as well as mobile communications. In future wireless communication systems, the energy efficiency of terminals and base stations has to be improved significantly. Therefore, we propose a new utility function, which is the difference of the capacity and a weighted power cost term. The gen...
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We consider the lifetime optimization problem for multicasting in wireless ad hoc networks, in which each node is equipped with a directional antenna and has limited energy supplies. Several distributed algorithms proposed recently are especially beneficial to a resource-constrained wireless ad hoc network. In this paper, we propose a new distributed algorithm and investigate its theoretical perfo...
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This paper discusses a ranging algorithm appropriate for impulse radio ultra-wideband signals compliant with the IEEE 802.15.4a standard. Three steps are indicated to locate the so-called ranging marker in the received signal. The first is to find the highest peaks in the channel responses to the transmitted pulses. The second consists in measuring the distance of each peak to the starting time of...
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Constellation subset selection (CSS) is a new topic emerging in the adaptive modulation communications. How to choose the subset of the original constellation phasers appears to be challenging and interesting to the researchers. There hardly exists any literature which studies the feasibility and the solution of constellation subset selection in details. Here we dedicate to this problem in both th...
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The rapid proliferation of wireless sensor networks has stimulated enormous research efforts that aim to maximize the lifetime of battery-powered sensor nodes and, by extension, the overall network lifetime. Most work in this field can be divided into two equally important threads, namely (i) energy-efficient routing that balances traffic load across the network according to energy-related metrics...
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In this paper, we study multi-hop non-regenerative multiple-input multiple-output (MIMO) relay communications with any number of hops. We design the optimal source precoding matrix and the optimal relay amplifying matrices for such relay network where a nonlinear minimal mean-squared error (MMSE)-decision feedback equalizer (DFE) is used at the destination node. We first derive the structure of th...
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The goal of this paper is to explore the benefits of channel diversity in wireless ad hoc networks. Our model is that of a Poisson point process of transmitters, each with a receiver at a given distance. A packet is divided in blocks which are transmitted over different subbands determined by random frequency hopping. At the receiver, a maximum-likelihood decoder is employed to estimate the transm...
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This paper proposes a framework for distributed sequential parameter estimation in wireless sensor networks. In the proposed scheme, the estimator is updated sequentially at the current node with its new measurement and the noisy corrupted local estimator from the previous node. Since all nodes in the network may not carry useful information, methodologies to find the best set of nodes and the cor...
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Femtocell is an effective solution to improve indoor coverage for cellular networks, where short-range and low-power Base Stations (BSs) called Femto BSs are deployed in small areas (e.g., buildings). We propose the Femto Private Branch Exchange (FPBX) to concentrate the traffic of the Femto BSs in a specific area, such as a campus or an enterprise with central or distributed locations. Through th...
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In this paper, we propose a new design strategy based on the minimum mean-squared error (MMSE) in closed-loop non-regenerative multiple-input multiple-output relaying systems. Instead of conventional singular value decomposition based methods, we address the problem for joint MMSE design in a different approach using the Wiener filter solution which leads to simple derivations of the optimal MMSE ...
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This paper proposes a simple non-coherent amplify-and-forward receiver for the relay channel and evaluates its diversity performance for Rayleigh fading channels. We use the generalized likelihood ratio test to obtain the decision rule in closed form, independent of the fading distribution. The receiver is developed for M-ary orthogonal signals and multiple relays. The only side information requir...
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